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.. meta::
  :description: Documents cuda::std::variant in libhipcxx, a type-safe union type available from C++14 with constexpr support and a recursion-based cuda::std::visit implementation.
  :keywords: libhipcxx, ROCm, HIP, C++, variant, type-safe union, constexpr, visit, cuda::std::visit

.. _libcudacxx-standard-api-utility-variant:

``<cuda/std/variant>``
======================

This page documents ``cuda::std::variant`` in libhipcxx, a type-safe union that holds one of a set of types, available from C++14 onwards with constexpr support.

See the documentation of the standard header `\<variant\> <https://en.cppreference.com/w/cpp/header/variant>`_

Extensions
----------

- All features are available from C++14 onwards.
- All features are available at compile time if the different value types support it.

Restrictions
------------

On device no exceptions are thrown in case of a bad access.

Implementation notes
--------------------

``cuda::std::visit`` uses recursion instead of the usual array of function pointers. This improves runtime behavior
at the cost of longer compile times.